This document provides an overview of a student project on an automated water filling and charging station system using a programmable logic controller (PLC). It includes an abstract, table of contents, and chapters on the project overview, PLC history and architecture, system components like switch mode power supplies and relays, and the planned wiring diagram and programming. The project aims to design and develop a system that can automatically fill water and charge devices to provide convenience to users.

1. 1
A PROJECT REPORT
ON
TOPIC
Automated water filling and Charging Station
Based on PLC
BACHELOR OF TECHNOLOGY
IN
ELECTRICAL ENGINEERING
SESSION (2018-19)
SUBMITTED TO: SUBMITTED BY:
Raju Swami (HOD) Name of Student
1. Abhishak Jain
2. Devansh Sharma
3. Geetanjali Maghwal
4. Mayank Mathur
Name of Department Branch & Semester
Electrical Engg. Electrical VIIth Sem.

2. 2
FACULTY OF ENGINEERING,
PACIFIC UNIVERSITY, Udaipur
CERTIFICATE
This is certified that Miss. Geetanjali Meghwal and Mr. Abhishak Jain, Devansh Sharma,
Mayank Mathur student of 7th semester of Electrical Engineering from Faculty of
Engineering, Udaipur has successfully completed their Minor Project on Automated
Water filling and Phone Charging Based on PLC.
The nature of work seen and observe perform by them during the Minor Project work was
Excellent. The students were punctual and hardworking. There work was up to the
standard of Pacific University, Udaipur.
We wish good luck for their future.
Raju Swami Jitendra Kasera
(Head) (Project Guide)

3. 3
ACKNOWLEDGEMENT
This is opportunity to express our heart full words for the people who were part of this
training in numerous ways, people who gave us as unending support right from beginning of
the training.
We are grateful to project Guide Mr. Arpit Sir for giving guidelines to make the project
successful.
We extend our thanks to Mr. Raju Swami Head of the Department for his cooperation and
guidance.
We want to give sincere thanks to one & only Jitendra Kasera Sir for his valuable support.
Last but not least we would like to thank YouTube & Wikipedia for their valuable support.
Yours Sincerely,
(Student Name)
1. Abhishek Jain
2. Devansh Sharma
3. Geetanjali Meghwal
4. Mayank Mathur

4. 4
Abstract
The objective of our project is to design, develop and monitor “Automatic water filling and charging
station, system using PLC”. This work provides with a lot of benefits like low power consumption,
low operational cost, less maintenance, accuracy and many more. This project is based on Industrial
automation and is a vast application used in many industries like highways, food court, mineral water
and many industrial manufacturers. A prototype has been developed to illustrate the project.
Most people nowadays use chargeable devices such as smart phones, tablets, laptops, media players.
When these gadgets ran out of battery there is always that need to be able to charge the device. An
automatic charging station caters to all users of any chargeable gadget. The study used the
experimental method and it was accomplished by fabricating the device including the wirings of
components and programming the PLC. The device was evaluated on its functionality and efficiency.
The device was highly functional and efficient as results showed an increase in battery life and equal
charging time compare to standard time.

5. 5
Table of Content
1. Project Overview
1.1 Introduction
1.2 Process
1.3 Hardware Description
1.4 Project Goals
2. About PLC
2.1 History of PLC
2.2 PLC Architecture
2.3 Parts of Programmable Controller
2.3.1 Input /Output Section
2.3.2 The Processor
 Input Image Table
 Output Image Table
 Central Processing Unit
 User Program Memory
 The Complete Scan Cycle
 Data Memory
 Operating System of PLC
2.4 System Overview
2.4.1 The CPU
2.4.2 Input / Output Section
2.4.3 Timer / Counter
2.4.4 Serial Communication
2.4.5 Programming Device
2.4.6 Power Supply Unit

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3. Switch Maode Power Supply
3.1 Introduction
3.2 Explanation
3.3 Advantage and Disadvantage
3.4 Switch Mode Power Supply’s Working Principle
3.4.1 DC to DC Converter SMPS Working Principle
3.4.2 AC to D Converter SMPS Working Principle
3.4.3 Fly-Back Converter type SMPS Working principle
3.4.4 Forward Converter type SMPS Working
3.5 Forward Converter type SMPS
4. Relay
4.1 Introduction to Relay
4.2 History of Relay
4.3 Type of Relay
4.3.1 SPST-NO Type Relay
4.3.2 SPST NC Type Relay
4.3.3 SPDT Type Relay
4.3.4 DPST Type Relay
4.3.5 DPDT Type Relay
4.4 Application
5. Sensor
5.1 Introduction to Proximity Sensor
5.2 Type of Sensors
5.3 Application
5.4 Why two types
5.5 Use with a Programmable logic Controller (PLC)
6. Description of all the Components
6.1 SMPS

7. 7
6.2 Relay
6.3 Allen Bradely Micrologix 1000
6.4 Sensor
6.5 Pump
6.6 Push Buttons
6.7 Indication Lamp
7. Wiring Diagram & Programming of Project
7.1 Wiring Diagram of Project
7.2 Programming of Project

8. 8
Chapter 1
Project Overview

9. 9
Project Overview
Introduction-
Most people now a day’s use so many electronic devices which may be smart phones,
tablets, etc. This runs on battery and many times low battery could cause some problems. So
the goal of this project is to give user the advantage to charge their electronic devices and
provide drinkable water.
The device is able of doing both the things at a same time, it can charge your device
and also at the same time it also provides drinkable water. And of course it takes charge,
nothing is free. So the user gets all the advantages after the insertion of a coin.
Process-
Step1- Selection
The project allows the user to choose from 3 different operations. Which are as
follows.
1 Charging
2 Water
3 Both
Step2- Coin Insertion
Step 3- Start Button
After completing the above 3 steps the device will start the selected process. Now it must be
clear that the selected actions will only work for a selected time. During the process the user
will get notification of continuation of work through the Indication lamps. The indication
lamps will glow normally when the project is not used and will start to blink as the process
starts. The indication light will continue to blink throughout the process.
Hardware Description-
 There are 2 indication lamps for the indication purpose so that the user get to know
about what process he/she has selected and what process is currently running now.
 3 Selection switches which are as follows.
 Button 1->Water, Charging, Both
 Button 2-> ON
 Button 3-> OFF
 Multiport charging cable because all phones don’t have same charging port so the
user can choose which cable supports his/her device’s port.

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 PLC it is called Programmable Logical Controller. It is used for the purpose of
automation. PLC’s reduce the complexity of the RLC.
 SMPS (Switching Module Power Supply) is a power supply that uses a switching
regulator to control and stabilize the output.
 Wiring are used for the interconnection of the devices.
 Relays are used for switching purposes.
 Sensors are used for the sensing of insertion of the coin.
 Pumps are used for the water supply. To the outlet of the device.
Project Goal-
 To gain knowledge about the connections to be done in all different devices
 How to select a device according to the usage and requirement.
 To know about different devices available in the market.
 To efficiently make a wiring diagram of the available devices.

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Chapter 2
About PLC

12. 12
History Of PLC –
Programmable logic controllers (PLCs) first hit the scene in the late 1960s. The
primary reason for designing such a device was eliminating the large cost involved in
replacing the complicated relay based machine control systems for major U.S. car
manufacturers.
Some companies proposed schemes based on the Digital Equipment Corp. DEC PDP-
8, the widely-used mini-computer at the time. Dick Morley’s company Bedford
Associates in Massachusetts proposed something called a Modular Digital Controller
(MODICON). The MODICON 084 brought the world’s first PLC into commercial
production.
Since then, a slow steady growth has allowed the manufacturing and process control
industries to take advantage of PLC applications-oriented software—programmable
language that looks and feels like relay-ladder-logic where any maintenance
technician.
Morley is generally credited with the “invention” of the PLC. However, there were
many others involved in the birth of this landmark development, including the late
Odo Struger (from Allen-Bradley, now Rockwell).
Morley said details of the PLC came about on 1 January 1968. Some 35 years later, it
is arguably the most widely used product in the industrial automation business, with a
worldwide market of several billions of dollars per year. PLC products are available
from hundreds of different sources, in many different form-factors (including
embedded controllers), and with prices ranging from tens of thousands of dollars (for
triple redundant, failure-proof systems) to commodity products at less than a hundred
bucks.
Take a look at this History of the PLC, as told to Howard Hendricks by Dick Morley
himself. In true Morley fashion, he calls these “fables,” which may or may not have a
basis of truth; but he insists, they are the best that his memory can do after all this
time.
PLC ARCHITECTURE
PLCs contain three basic sections:
 Central processing unit (CPU)
 Memory: EPROM, RAM, and so on
 Input/output section for communication with peripherals (ADC, DAC).

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A PLC is basically a black box with a number of inputs from, and a number of outputs to,
the outside world. It can make decisions, store data, do timing cycles, do simple
arithmetic, convert codes, and so on. The basic difference between this black box and a
hardware logic system using IC chips or a relay controlled system, is that specific coded
messages are stored in areas called program memory, which are PROM or ROM and
RAM chips. It is, however, much easier to change a program when a different process is
required than to rewire the control system. For example, it may take electricians a
couple of weeks to require a pipe mill, whereas a programmer will spend only a fraction
of this time to reprogram a PLC since no wires will have to be changed. In addition,
various recipes can be stored in memory and accessed when required, making the
program extremely flexible.
The system operates through interaction with the processor and program memory. When
the power to the system is turned on, the processor reads the first instruction stored in
memory and acts on this instruction. When completed, it goes back to the memory for the
next instruction, and so on until task is complete. This operation is called the fetch-
execute cycle. The processor communicates with the outside world via input and output
modules.
THE PARTS OF A PROGRAMMABLE CONTROLLER

14. 14
Programmable logic controllers (PLC) can be considered to have three parts:
1. Input/output Section
The I/O section contains input modules and output modules. Functionally, the input
modules are equivalent to the signal converters (i.e. Analog to Digital or high power to
low power). All modern PLC input modules use optical devices to accomplish electrically
isolated coupling between the input circuit and the processor electronics.
Each input device is wired to a particular input terminal on the I/O section. Thus if the
switch is closed, 5v dc appears on input terminal, converts this dc voltage to a digital 1
and sends it to the processor via programmable peripheral interface (PPI). Conversely,
if the switch is open, no dc voltage appears on input terminal. Input section will respond
to this condition by sending a digital 0 to the processor. The other input terminals
behave identically.
2. The Processor
The processor of a PLC holds and executes the user program. In order to carry out this
job, the processor must store the most up-to-date input and output conditions.
(a) Input image table:
The input conditions are stored in the input image table, which is a portion of the
processor’s memory. That is, every single input module in the I/O section has assigned to
it a particular location within the input image table. That particular location is
dedicated solely to the task of keeping track of the latest condition of its input terminal.
As mentioned in earlier section, if the input terminal has 5v dc power fed to it by its input
device, the location within the input image table contains a binary 1(HI); if the input
terminal has no 5v dc power fed to it, the location contains a binary 0(LO).
The processor needs to know the latest input conditions because the user program
instructions are contingent upon those conditions. In other words, an individual
instruction may have one outcome if a particular input is HI and a different outcome if
that input is LO.
(b) Output image table:
The output conditions are stored in the output image table, which is another portion of
the processor’s memory. The output image table bears the same relation to the output
interface of the I/O section that while terminals are analog inputs. You can directly
connect any analog input to the processor via these terminals. Analog signal from these
terminals is first converted to digital value via programmable peripheral interface (PPI).
The I/O section’s output modules are functionally the same as the output amplifiers.
They receive a low power digital signal from the processor and convert it into a high
power signal capable of driving an industrial load. A modern PLC output module is

15. 15
optically isolated, and uses a triac, power transistor or relay as the series connected load
controlling device. Terminal 1 to 8 are these type of O/P terminals whereas terminal D/A
is Analog output terminal from processor. Each output device is wired to a particular
output terminal on the I/O interface. Thus, for example, if output module 1 receives a
digital 1 by applying 5v dc to output terminal 1, thereby illuminating LED is
extinguished.
Besides 5v dc (TTL devices), I/O module are also for interfacing to other industrial
levels, including 12v dc.
The input image table bears to the input modules. That is, every single output module
has assigned to it a particular memory location is dedicated solely to the task of keeping
track of the latest condition of its output module.
Of course, the output situation differs from the input situation with regard to the direction
of information flow is from the output image table to the output modules, while in the
input situation the information flow is from the input modules to the input image table.
The locations within the input and output image tables are identified by addresses, which
refers to unique address of each terminal.
(c) Central processing unit:
The subsection of the processor that actually performs the program execution will be
called the central processing unit (CPU) with reference to input and output image
table CPU executes the user program and continuously updates the output image
table.
The output image table has a dual nature; its first function is to receive immediate
information from the CPU and pass if on to the output modules of the I/O section; but
secondly, it also must be capable of passing output information “backward” to the
CPU, when the user program instruction that the CPU is working on calls for an item
of output information. The input image table does not have its dual nature. Its single
mission is to acquire information from the input modules and pass that information
“forward” to the CPU when the instruction that the CPU is working on calls for an
item of input information.
(d) User program memory:
A particular portion of the processor’s memory is used for storing the user program
instructions. We will use the name user program memory to refer to this processor
subsection.
Before a PLC can begin controlling an industrial system, a human user must enter the
coded instructions that make up the user program. This procedure called programming
the PLC.

16. 16
As the user enters instructions, they are automatically stored at sequential locations
within the user program memory. This sequential placement of program instructions is
self-regulated by the PLC, with no discretion needed by the human user.
The total number of instructions in the user program can range from a half dozen or so,
for controlling a simple machine, to several thousand, for controlling a complex machine
or process.
After the programming procedure is complete, the human user manually switches the
PLC out to PROGRAM mode into RUN mode, which causes the CPU to start executing
the program from beginning to end repeatedly.
(e) The complete scan cycle:
As long as the PLC is left in the RUN mode, the processor executes the user program over
and over again. Figure depicts the entire repetitive series of events. Beginning at the top
of the circle representing the scan cycle, the first operation is the input scan. During the
input scan, the current status of every input module is stored in the input image table,
bringing it up to date.
Following the input scan, the processor enters its user program execution. Sometimes
called “program scan”. The program executes with reference to input and output image
tables and updates output image table.
Throughout the user program execution, the processor continuously keeps its output
image table up to date, as stated earlier. However, the output modules themselves are not
kept continuously up to date. Instead, the entire output image table is transferred to the
output module during the output scan following the program execution.
(f) Data Memory:
A PLC is a computer, after all. Therefore, it can perform arithmetic, numeric
comparisons, counting, etc. Naturally the numbers and data can change from one scan
cycle to the next. Therefore the PLC must have a section of its memory set aside for
keeping track of variable data, or numbers, that are involved with the user program. This
section of memory we will call data memory.
When the CPU is executing an instruction for which a certain data value must be known,
that data value is brought in from data memory. When the CPU executes an instruction
that provides a numerical result, that result is put out into data memory. Thus, CPU can
read from or write to the data memory. Understand that this relationship is different
from the relationship between the CPU and the user program memory. When the user
program is executing, the CPU can only reads from the user program memory, never
write to it.

17. 17
(g) Operating System of PLC:
The function of the operating system is to present the user with the equivalent of an
extended machine or virtual machine that is easier to program than the underlying
hardware.
Due to this operating system, PLC is very easy to program. It can be programmed using
electrical schemes with familiar relay symbols so that a plant electrician can easily
access the PLC. Even though he does not know the assembly language or even if he may
not have any familiarity with computers and electronics, he will be able to program the
PLC.
The function of PLC Operating system is:
1. Loads the user program from programming device to program memory.
2. To read status of input devices.
3. To execute user program.
4. To form and update input image table.
5. As per the status of output image table controls the output devices.
6. To provide user-friendly functions.
This O.S. makes supervision over entire system, so O.S. Programs are said to running
in supervisory mode.
When the user completely enters his program in user memory, he transfers control
from PROGRAM mode to RUN mode. In RUN mode the control of the whole system
is transferred to operating system. Now operating system takes care of the whole
system such that the whole system becomes automatic and appears as magic to users.
SYSTEM OVERVIEW:
This low cost PLC system was designed to satisfy hunger of Automation of Indian
Industry and also helps beginners as well as development engineers to get into
Automation field.
System consist of following main sections:
(1) The CPU:

18. 18
The CPU uses the 89c51 microcontroller, which operates at 11.0592Mhz. It has 8k
RAM, which can be used as data memory, 8k RAM that can be used as program
memory as well as data memory, 8k EEPROM that can be used as program memory.
(2) Input/output Section:
This part of system is on separate board connected to processor via cable. It allows
the processor to communicate with the outside world. It is also called Data
Acquisition System (DAS).
This part of system provides 4 digital inputs consisting of 2 dc and 2 ac, 4 digital
outputs consisting of 2 dc and 2 ac each. It also provides 8 analog inputs with
following ranges:
1. –5v to +5v (one channel).
2. 0v to 10v (one channel).
3. 4mA to 20mA (one channel).
4. 0v to 5v (five channel).
(3) Timer/Counter:
The system has 2 timers or 2 counters or 1 timer and 1 counter. The timer provides
maximum of 255sec delay and the counter provides maximum of 255 counts.
(4) Serial Communication:
The system uses RS-232 serial data standard. Chip ICL232 is used as communication
interface between RS-232 standard and TTL logic.
(5) Programming Device:
This system uses personal computer (PC) as programming device. The user can write
program in user friendly language. The programming devices (PC) converts this user
friendly language program into machine understandable language and transmit it to
the PLC board via serial communication.
(6) Power Supply Unit:
This system provides +12v and -12v with maximum 2amps and +5v with maximum of
1amps.

19. 19
Chapter 3
Switch Mode Power Supply

20. 20
Introduction-
A switched-mode power supply (switching-mode power supply, switch-mode power
supply, switched power supply, SMPS, or switcher) is an electronic power supply that
incorporates a switching regulator to convert electrical power efficiently. Like other power
supplies, an SMPS transfers power from a DC or AC source (often mains power) to DC
loads, such as a personal computer, while converting voltage and current characteristics.
Unlike a linear power supply, the pass transistor of a switching-mode supply continually
switches between low-dissipation, full-on and full-off states, and spends very little time in the
high dissipation transitions, which minimizes wasted energy. Ideally, a switched-mode power
supply dissipates no power. Voltage regulation is achieved by varying the ratio of on-to-off
time. In contrast, a linear power supply regulates the output voltage by continually
dissipating power in the pass transistor. This higher power conversion efficiency is an
important advantage of a switched-mode power supply. Switched-mode power supplies may
also be substantially smaller and lighter than a linear supply due to the smaller transformer
size and weight.
Switching regulators are used as replacements for linear regulators when higher efficiency,
smaller size or lighter weights are required. They are, however, more complicated; their
switching currents can cause electrical noise problems if not carefully suppressed, and
simple designs may have a poor power factor.
Explanation-
A linear regulator provides the desired output voltage by dissipating excess power
in ohm (e.g., in a resistor or in the collector–emitter region of a pass transistor in its active
mode). A linear regulator regulates either output voltage or current by dissipating the excess
electric power in the form of heat, and hence its maximum power efficiency is voltage-
out/voltage-in since the volt difference is wasted.
In contrast, a switched-mode power supply changes output voltage and current by switching
ideally lossless storage elements, such as inductors and capacitors, between different
electrical configurations. Ideal switching elements (approximated by transistors operated
outside of their active mode) have no resistance when "on" and carry no current when "off",
and so converters with ideal components would operate with 100% efficiency (i.e., all input
power is delivered to the load; no power is wasted as dissipated heat).
The basic schematic of a boost converter.
For example, if a DC source, an inductor, a switch, and the corresponding electrical
ground are placed in series and the switch is driven by a square wave, the peak-to-peak
voltage of the waveform measured across the switch can exceed the input voltage from the
DC source. This is because the inductor responds to changes in current by inducing its own
voltage to counter the change in current, and this voltage adds to the source voltage while

21. 21
the switch is open. If a diode-and-capacitor combination is placed in parallel to the switch,
the peak voltage can be stored in the capacitor, and the capacitor can be used as a DC
source with an output voltage greater than the DC voltage driving the circuit. This boost
converter acts like a step-up transformer for DC signals. A buck–boost converter works in a
similar manner, but yields an output voltage which is opposite in polarity to the input
voltage. Other buck circuits exist to boost the average output current with a reduction of
voltage.
In an SMPS, the output current flow depends on the input power signal, the storage elements
and circuit topologies used, and also on the pattern used (e.g., modulation with an
adjustable duty cycle) to drive the switching elements. The spectral density of these switching
waveforms has energy concentrated at relatively high frequencies. As such, switching
transients and ripple introduced onto the output waveforms can be filtered with a small LC
filter.
Advantages and disadvantages
The main advantage of the switching power supply is greater efficiency than linear
regulators because the switching transistor dissipates little power when acting as a switch.
Other advantages include smaller size and lighter weight from the elimination of heavy line-
frequency transformers, and comparable heat generation. Standby power loss is often much
less than transformers.
Disadvantages include greater complexity, the generation of high-amplitude, high-frequency
energy that the low-pass filter must block to avoid electromagnetic interference (EMI),
a ripple voltage at the switching frequency and the harmonic frequencies thereof.
Very low cost SMPSs may couple electrical switching noise back onto the mains power line,
causing interference with A/V equipment connected to the same phase. Non-power-factor-
corrected SMPSs also cause harmonic distortion.

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Switch Mode Power Supply’s Working Principle
The working of a few types of switch-mode power supply topologies is as follows:
1. DC to DC Converter SMPS Working Principle
In a DC-to-DC converter, primarily a high-voltage DC power is directly obtained
from a DC power source. Then, this high-voltage DC power is switched at a very high
switching speed usually in the range of 15 KHz to 50 KHz.
And then it is fed to a step-down transformer which is comparable to the weight and
size characteristics of a transformer unit of 50Hz. The output of the step-down
transformer is further fed into the rectifier. This filtered and rectified output DC
power is used as a source for loads, and a sample of this output power is used as a
feedback for controlling the output voltage.With this feedback voltage, the ON time of
the oscillator is controlled, and a closed-loop regulator is formed.
DC to DC converter SMPS
The output of the switching-power supply is regulated by using PWM (Pulse Width
Modulation). As shown in the circuit above, the switch is driven by the PWM
oscillator, such that the power fed to the step-down transformer is controlled
indirectly, and hence, the output is controlled by the PWM, as this pulse width signal
and the output voltage are inversely proportional to each other.
If the duty cycle is 50%, then the maximum amount of power is transferred through
the step-down transformer, and, if duty cycle decreases, then the amount of power
transferred will decrease by decreasing the power dissipation.
2. AC to DC Converter SMPS Working Principle
The AC to DC converter SMPS has an AC input. It is converted into DC by
rectification process using a rectifier and filter. This unregulated DC voltage is fed to
the large-filter capacitor or PFC (Power Factor Correction) circuits for correction of
power factor as it is affected. This is because around voltage peaks, the rectifier
draws short current pulses having significantly high-frequency energy which affects
the power factor to reduce.

23. 23
AC to DC converter SMPS
It is almost similar to the above discussed DC to DC converter, but instead of direct
DC power supply, here AC input is used. So, the combination of the rectifier and
filter, shown in the block diagram is used for converting the AC into DC and
switching is done by using a power MOSFET amplifier with which very high gain can
be achieved. The MOSFET transistor has low on-resistance and can withstand high
currents. The switching frequency is chosen such that it must be kept inaudible to
normal human beings (mostly above 20KHz) and switching action is controlled by a
feedback utilizing the PWM oscillator.
This AC voltage is again fed to the output transformer shown in the figure to step
down or step up the voltage levels. Then, the output of this transformer is rectified
and smoothed by using the output rectifier and filter. A feedback circuit is used to
control the output voltage by comparing it with the reference voltage.
3. Fly-back Converter type SMPS Working Principle
The SMPS circuit with very low output power of less than 100W (watts) is usually of
Fly-back converter type SMPS, and it is very simple and low- cost circuit compared to
other SMPS circuits. Hence, it is frequently used for low-power applications.
Fly-back Converter type SMPS
The unregulated input voltage with a constant magnitude is converted into a desired
output voltage by fast switching using a MOSFET; the switching frequency is around
100 kHz. The isolation of voltage can be achieved by using a transformer. The switch

24. 24
operation can be controlled by using a PWM control while implementing a practical
fly-back converter.
Fly-back transformer exhibits different characteristics compared to general
transformer. The two windings of the fly-back transformer act as magnetically
coupled inductors. The output of this transformer is passed through a diode and a
capacitor for rectification and filtering. As shown in the figure, the voltage across this
filter capacitor is taken as the output voltage of the SMPS.
4. Forward Converter type SMPS Working
Forward converter type SMPS is almost similar to the Fly-back converter type SMPS,
but in the forward converter type, a control is connected for controlling the switch
and at the output of the secondary winding of the transformer, and the rectification
and filtering circuit is complicated as compared to the fly-back converter.
It can be called as a DC to DC buck converter, along with a transformer used for
isolation and scaling. In addition to the diode D1 and capacitor C, a diode D2 and an
inductor L are connected at the output end. If switch S gets switched ON, then the
input is given to the primary winding of the transformer, and hence, a scaled voltage
is generated at the secondary winding of the transformer.
Forward Converter type SMPS
Thus, the diode D1 gets forward biased and scaled voltage is passed through the low-
pass filter preceding the load. If the switch S is turned off, then the currents through
the primary and secondary winding reach to zero, but the current through the
inductive filter and load can not be change abruptly, and a path is provided to this
current by the freewheeling diode D2. By using the filter inductor, the required
voltage across the diode D2 and to maintain the EMF required for maintaining the
continuity of the current at inductive filter.
Even though the current is diminishing against the output voltage, approximately the
constant output voltage is maintained with the presence of the large capacitive filter.
It is frequently used for switching applications with a power in the range of 100 W to
200 W.

25. 25
Different types of topologies are there in which SMPS can be realized such as Buck
converter, Boost converter, Self Oscillating fly-back converter, Buck-boost converter,
Boost-buck, Cuk, Sepic. But only a few are discussed in this article, namely DC to DC
converter, AC to DC converter, Fly-back converter and Forward converter. For more
information regarding the types of switch-mode power supply and the types of SMPS
with their working principles, feel free to write your comments for improving this
article technically so that you can help the other readers to get awareness of SMPS.

26. 26
Chapter 4
Relay

27. 27
Introduction to Relay-
A relay is an electrically operated switch. Many relays use an electromagnet to mechanically
operate a switch, but other operating principles are also used, such as solid-state relays.
Relays are used where it is necessary to control a circuit by a separate low-power signal, or
where several circuits must be controlled by one signal. The first relays were used in long
distance telegraph circuits as amplifiers: they repeated the signal coming in from one circuit
and re-transmitted it on another circuit. Relays were used extensively in telephone exchanges
and early computers to perform logical operations.
Magnetic latching relays require one pulse of coil power to move their contacts in one
direction, and another, redirected pulse to move them back. Repeated pulses from the same
input have no effect. Magnetic latching relays are useful in applications where interrupted
power should not be able to transition the contacts.
Magnetic latching relays can have either single or dual coils. On a single coil device, the
relay will operate in one direction when power is applied with one polarity, and will reset
when the polarity is reversed. On a dual coil device, when polarized voltage is applied to the
reset coil the contacts will transition. AC controlled magnetic latch relays have single coils
that employ steering diodes to differentiate between operate and reset commands.
History of Relay-
In 1833, Carl Friedrich Gauss and Wilhelm Weber developed an electromagnetic relay.
American scientist Joseph Henry is often claimed to have invented a relay in 1835 in order to
improve his version of the electrical telegraph, developed earlier in 1831.
It is claimed that English inventor Edward Davy "certainly invented the electric relay"[6]
in
his electric telegraph c.1835.
A simple device, which is now called a relay, was included in the original
1840 telegraph patent of Samuel Morse The mechanism described acted as a digital
amplifier, repeating the telegraph signal, and thus allowing signals to be propagated as far
as desired.
The word relay appears in the context of electromagnetic operations from 1860.
Type of Relay-
Since relays are switches, the terminology applied to switches is also applied to relays; a
relay switches one or more poles, each of whose contacts can be thrown by energizing the
coil. Normally open (NO) contacts connect the circuit when the relay is activated; the circuit
is disconnected when the relay is inactive. Normally closed (NC) contacts disconnect the
circuit when the relay is activated; the circuit is connected when the relay is inactive. All of
the contact forms involve combinations of NO and NC connections.
The National Association of Relay Manufacturers and its successor, the Relay and Switch
Industry Association define 23 distinct electrical contact forms found in relays and
switches.Of these, the following are commonly encountered:

28. 28
 SPST-NO (Single-Pole Single-Throw, Normally-Open) relays have a single Form
A contact or make contact. These have two terminals which can be connected or
disconnected. Including two for the coil, such a relay has four terminals in total.
 SPST-NC (Single-Pole Single-Throw, Normally-Closed) relays have a single Form
B or break contact. As with an SPST-NO relay, such a relay has four terminals in
total.
 SPDT (Single-Pole Double-Throw) relays have a single set of Form C, break before
make or transfer contacts. That is, a common terminal connects to either of two
others, never connecting to both at the same time. Including two for the coil, such a
relay has a total of five terminals.
 DPST – Double-Pole Single-Throw relays are equivalent to a pair of SPST switches
or relays actuated by a single coil. Including two for the coil, such a relay has a total
of six terminals. The poles may be Form A or Form B (or one of each; the
designations NO and NCshould be used to resolve the ambiguity).
 DPDT – Double-Pole Double-Throw relays have two sets of Form C contacts. These
are equivalent to two SPDT switches or relays actuated by a single coil. Such a relay
has eight terminals, including the coil
Application-
Relays are used wherever it is necessary to control a high power or high voltage circuit with
a low power circuit, especially when galvanic isolation is desirable. The first application of
relays was in long telegraph lines, where the weak signal received at an intermediate station
could control a contact, regenerating the signal for further transmission. High-voltage or
high-current devices can be controlled with small, low voltage wiring and pilots switches.
Operators can be isolated from the high voltage circuit. Low power devices such
as microprocessors can drive relays to control electrical loads beyond their direct drive

29. 29
capability. In an automobile, a starter relay allows the high current of the cranking motor to
be controlled with small wiring and contacts in the ignition key.
Electromechanical switching systems including Strowger and Crossbar telephone exchanges
made extensive use of relays in ancillary control circuits. The Relay Automatic Telephone
Company also manufactured telephone exchanges based solely on relay switching techniques
designed by Gotthilf Ansgarius Betulander. The first public relay based telephone exchange
in the UK was installed in Fleetwood on 15 July 1922 and remained in service until 1959.
The use of relays for the logical control of complex switching systems like telephone
exchanges was studied by Claude Shannon, who formalized the application of Boolean
algebra to relay circuit design in A Symbolic Analysis of Relay and Switching Circuits.
Relays can perform the basic operations of Boolean combinatorial logic. For example, the
boolean AND function is realised by connecting normally open relay contacts in series, the
OR function by connecting normally open contacts in parallel. Inversion of a logical input
can be done with a normally closed contact. Relays were used for control of automated
systems for machine tools and production lines. The Ladder programming language is often
used for designing relay logic networks.
Early electro-mechanical computers such as the ARRA, Harvard Mark II, Zuse Z2, and Zuse
Z3 used relays for logic and working registers. However, electronic devices proved faster
and easier to use.
Because relays are much more resistant than semiconductors to nuclear radiation, they are
widely used in safety-critical logic, such as the control panels of radioactive waste-handling
machinery. Electromechanical protective relays are used to detect overload and other faults
on electrical lines by opening and closing circuit breakers.

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Chapter 5
Sensor

31. 31
Introduction to proximity Sensor-
A proximity sensor is a sensor able to detect the presence of nearby objects without any
physical contact.
A proximity sensor often emits an electromagnetic field or a beam of electromagnetic
radiation (infrared, for instance), and looks for changes in the field or return signal. The
object being sensed is often referred to as the proximity sensor's target. Different proximity
sensor targets demand different sensors. For example, a capacitive proximity
sensor or photoelectric sensor might be suitable for a plastic target; an inductive proximity
sensor always requires a metal target.
Proximity sensors can have a high reliability and long functional life because of the absence
of mechanical parts and lack of physical contact between the sensor and the sensed object.
Proximity sensors are also used in machine vibration monitoring to measure the variation in
distance between a shaft and its support bearing. This is common in large
steam turbines, compressors, and motors that use sleeve-type bearings.
Use with mobile telephones and tablet computer
Proximity sensors are commonly used on mobile devices. When the target is within nominal
range, the device lock screen UI will appear, thus emerging from what is known as sleep
mode. Once the device has awoken from sleep mode, if the proximity sensor's target is still
for an extended period of time, the sensor will then ignore it, and the device will eventually
revert into sleep mode. For example, during a telephone call, proximity sensors play a role in
detecting (and skipping) accidental touchscreen taps when mobiles are held to the ear.[1]
Proximity sensors can be used to recognise air gestures and hover-manipulations. An array
of proximity sensing elements can replace vision-camera or depth camera based solutions for
the hand gesture detection.
Types of sensors
An inductive proximity switch.
 Capacitive
 Capacitive displacement sensor
 Doppler effect (sensor based on doppler effect)
 Eddy-current
 Inductive
 Magnetic, including magnetic proximity fuse

32. 32
 Optical
 Photoelectric
 Photocell (reflective)
 Laser rangefinder
 Passive (such as charge-coupled devices)
 Passive thermal infrared
 Radar
 Reflection of ionising radiation
 Sonar (typically active or passive)
 Ultrasonic sensor
 Fiber optics sensor
 Hall effect sensor
Applications
 Ground proximity warning system for aviation safety
 Vibration measurements of rotating shafts in machinery
 Top dead centre (TDC)/camshaft sensor in reciprocating engines.
 Sheet break sensing in paper machine.
 Anti-aircraft warfare
 Roller coasters
 Conveyor systems
 Beverage and food can making lines
 Mobile devices
 Touch screens that come in close proximity to the face
 Attenuating radio power in close proximity to the body, in order to reduce radiation
exposure
 Automatic faucets
What is the difference between PNP and NPN when describing 3 wire connection of a
sensor?
Most industrial proximity sensors (inductive, capacitive, ultrasonic and photo electric) are
solid state.
The term solid state refers to the type of components used within the sensor. Solid state
electronic components such as transistors are used to switch the output of the sensor upon
detection of an object.
Two specific types of 3 wire sensors are available; PNP and NPN. The difference is a result
of the internal circuit design and type of transistors used.
A key point to observe is that PNP and NPN has nothing to do with whether the sensor
is normally open (N/O) or normally closed (N/C), i.e. a PNP sensor may be either N/O or
N/C as can an NPN be either N/O or N/C.
Why two types?

33. 33
The selection of a PNP sensor verses an NPN sensor is determined by the nature of the
circuit the device is to be used in. When used in a traditional relay type control circuit, it is
normally possible to use either the PNP or the NPN type of sensor as shown below. PNP
sensors tend to be more commonly used.
Traditional relay type control circuit;
Use with a programmable logic controller (PLC).
When selecting a sensor to be used with a PLC, it is very important that the sensor matches
the type of PLC input card to be used.
Two types of input cards exist, those that 'sink' current (also known as positive logic) and
those that 'source' current (also known as negative logic). It is worth mentioning, that whilst
the terms sinking / sourcing and positive / negative logic are well known in some industries,
they are not always commonly used terms. It is therefore important to identify the type
of sensor to be used with the PLC card based on the PLC manufacturer's documentation and
/ or wiring diagrams.

34. 34
Most common in Europe is the 'sinking' type of input, these will be used with the PNP sensor
as shown below. Less common nowadays are input cards that 'source', these were popular in
Asia and require the NPN type of sensor in order to operate correctly. Many modern
PLC input cards can be configured and wired to be either 'sinking' or 'sourcing' although it
will usually necessitate all inputs on a particular input card being configured the same.

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Chapter 6
Description of all the Components

36. 36
Devices used in Project-
S.No Name Quantity
1 PLC 1
2 SMPS 1
3 Push Button 3
4 Sensor 1
5 Indication Lamp 2
6 Pump 1
7 wiring -
8 Relay 2
1 SMPS-
A switched-mode power supply is an electronic power supply that incorporates a
switching regulator to convert electrical power efficiently. Like other power supplies,
an SMPS transfers power from a DC or AC source (often mains power) to DC loads,
such as a personal computer, while converting voltage and current characteristics.
Unlike a linear power supply, the pass transistor of a switching-mode supply
continually switches between low-dissipation, full-on and full-off states, and spends
very little time in the high dissipation transitions, which minimizes wasted energy.
Ideally, a switched-mode power supply dissipates no power. Voltage regulation is
achieved by varying the ratio of on-to-off time. In contrast, a linear power supply
regulates the output voltage by continually dissipating power in the pass transistor.
This higher power conversion efficiency is an important advantage of a switched-
mode power supply. Switched-mode power supplies may also be substantially smaller
and lighter than a linear supply due to the smaller transformer size and weight. In
this project, 24 V DC and 12 V DC SMPS had been used for the power supply of the
different components used. For example, 12 V DC is used to supply power to water
pump, DC geared motor and 24 V DC is used to supply power to the solenoid valve,
water float switch and photoelectric sensor.
2 Relay-
The main operation of a relay comes in places where only a low-power signal can be
used to control a circuit. It is also used in places where only one signal can be used to

37. 37
control a lot of circuits. The application of relays started during the invention of
telephones. They played an important role in switching calls in telephone exchanges.
They were also used in long distance telegraphy. They were used to switch the signal
coming from one source to another destination. After the invention of computers they
were also used to perform Boolean and other logical operations. The high end
applications of relays require high power to be driven by electric motors and so on.
Such relays are called contactors.
3 Allen Bradely Micrologix 1000-
A programmable logic controller (PLC) or programmable controller is an
industrial digital computer which has been ruggedized and adapted for the control of
manufacturing processes, such as assembly lines, or robotic devices, or any activity
that requires high reliability control and ease of programming and process fault
diagnosis.
They were first developed in the automobile manufacturing industry to provide
flexible, ruggedized and easily programmable controllers to replace hard-wired
relays, timers and sequencers. Since then they have been widely adopted as high-
reliability automation controllers suitable for harsh environments. A PLC is an
example of a "hard" real-time system since output results must be produced in
response to input conditions within a limited time, otherwise unintended operation
will result.
4 Sensor-
A inductive proximity sensor can detect metal targets approaching the sensor, without
physical contact with the target. Inductive Proximity Sensors are roughly classified
into the following three types according to the operating principle: the high-frequency
oscillation type using electromagnetic induction, the magnetic type using a magnet,
and the capacitance type using the change in capacitance.

38. 38
5 Pump-
Compact, submersible water pumps are mostly used on air coolers, aquariums, and
fountains. If the pump runs out of water and continues to operate — an issue known
as dry running — it can become damaged. This circuit protects submersible water
pumps from dry running with the help of associated level electrodes. The circuit
detects the absence of water and monitors the water level to prevent dry running from
occurring.
6 Push Buttons-
A push-button (also spelled pushbutton) or simply button is a
simple switch mechanism for controlling some aspect of a machine or a process.
Buttons are typically made out of hard material, usually plastic or metal. The surface
is usually flat or shaped to accommodate the human finger or hand, so as to be easily
depressed or pushed. Buttons are most often biased switches, although many un-
biased buttons (due to their physical nature) still require a spring to return to their
un-pushed state. Terms for the "pushing" of a button
include pressing, depressing, mashing, slapping, hitting, and punching.

39. 39
7 Indication Lamp-
A light-emitting diode (LED) is a two-lead semiconductor light source. It is a p–n
junction diode that emits light when activated.When a suitable current is applied to
the leads, electrons are able to recombine with electron holes within the device,
releasing energy in the form of photons. This effect is called electroluminescence, and
the color of the light (corresponding to the energy of the photon) is determined by the
energy band gap of the semiconductor. LEDs are typically small (less than 1 mm2
)
and integrated optical components may be used to shape the radiation pattern.

40. 40
Chapter 7
Wiring Diagram & Programming of
Project

41. 41
Wiring Diagram of Project-
Programming of Project-